PHILADELPHIA — The Eagles already have had a changing of the guard this season.

Now they’re experiencing a changing of the quarterback and running back.

Two days after announcing that rookie quarterback Nick Foles will start the final four games this season, coach Andy Reid revealed Wednesday that rookie running back Bryce Brown likely will remain in the starting lineup for the rest of the year.

Foles and Brown will replace Michael Vick and LeSean McCoy, respectively. Both Vick and McCoy are trying to recover from concussions and have yet to gain medical clearance. Considering the Eagles’ status at the bottom of the NFC, it makes sense to get an extended look at some of the younger players.

“It’s a great honor and I’m very fortunate to be in this situation,” Foles said Wednesday. “But I still have a lot of work to do. My mindset stays the same. I just have to keep taking this one day at a time and keep working as hard as I can.”

Foles, a third-round draft pick from the University of Arizona, will be making his fourth straight start at Tampa Bay on Sunday in relief of Vick. Reid said Wednesday that Vick, who suffered a concussion against Dallas on Nov. 11, had still not passed the ImPACT test. But even if he is cleared to play again this season, he will serve as Foles’ backup.

But despite the switch in the depth chart, there has been no tension among Foles and Vick, who has not been available for comment since getting hurt.

“With Mike and I, our relationship will stay the same,” Foles said. “What we say is between us, but I’ve always been supportive of Mike and I always will be. I think Mike is a great player, a great guy, and I’ll always think that. Our relationship hasn’t changed.”

Brown has maintained the same sort of rapport with McCoy, who has been unavailable to the media since he endured a concussion against Washington on Nov. 18.

Brown, who has started the last two games, said he constantly talks with his mentor and has received nothing but positive feedback.

“Shady (McCoy’s nickname) is real excited for me,” Brown said. “He just told me to keep playing with confidence.”

Foles has made gradual progress since taking over the offense.

He had a terrible NFL debut in relief of Vick against the Cowboys last month, throwing an interception and losing a fumble that both resulted in Dallas touchdowns. He also got off to a rocky start the following week against Washington, throwing two interceptions and completing just 21-of-46 passes.

In the last two games, he’s not committed any turnovers and has completed 38-of-55 passes for 370 yards and a touchdown.

“He’s done well up to this point,” Reid said. “But you’ve got to keep going. As teams have an opportunity to study you and your strengths and weaknesses, you have to be able to answer that. It’s a matter of just getting reps under his belt.”

Brown, a seventh-round draft pick, has been brilliant at times but also has demonstrated a penchant for coughing up the football.

He wowed Eagles fans in his first start against Carolina on Nov. 26 by rushing for 178 yards and two touchdowns on 19 carries but also fumbled twice in a 30-22 loss. Last Sunday, he tore through the Cowboys’ defense for 169 yards and two more TDs on 24 carries but lost a crucial fumble late in a 38-33 defeat.

His 347 yards in those games marked the second-highest two-game rushing total in franchise history behind Steve Van Buren’s 379 yards in back-to-back games in 1949.

Brown has not gone as far as Vick did earlier this season by carrying around a football to meals and meetings, but did work on holding onto it during practice on Wednesday.

“I had guys on the scout team trying to knock the ball out,” Brown said. “They almost got it twice, but I’m emphasizing holding the ball high and tight in my arm. There are no excuses. I’ve got to hang onto the football.”

“We know we have to run the ball and Bryce can do it,” Eagles tight end Brent Celek said. “He’s very explosive, very fast and does a good job of running hard in a straight line. And he’s going to get even better as he goes and gets more confidence.”